Update rollup

Point entry to correct path.

rollup.config.js

@@ -4,7 +4,7 @@ import typescript from '@rollup/plugin-typescript'
 
 import pkg from './package.json'
 
-const ENTRY_POINT = './index.ts'
+const ENTRY_POINT = './lib/index.ts'
 
 export default {
   input: ENTRY_POINT,